lavfi: port boxblur filter from libmpcodecs

With the following additions:
* support to gray format
* support to yuva420p format
* parametric luma/chroma/alpha radius
* consistency check on the radius values, avoid crashes with invalid values

4 files changed, 354 insertions, 2 deletions

diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index a8233fd764..e29fe5eabd 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -25,6 +25,7 @@ OBJS-$(CONFIG_ANULLSRC_FILTER)               += asrc_anullsrc.o
 OBJS-$(CONFIG_ANULLSINK_FILTER)              += asink_anullsink.o
 
 OBJS-$(CONFIG_BLACKFRAME_FILTER)             += vf_blackframe.o
+OBJS-$(CONFIG_BOXBLUR_FILTER)                += vf_boxblur.o
 OBJS-$(CONFIG_COPY_FILTER)                   += vf_copy.o
 OBJS-$(CONFIG_CROP_FILTER)                   += vf_crop.o
 OBJS-$(CONFIG_CROPDETECT_FILTER)             += vf_cropdetect.o
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index feae239626..8d80957cff 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -41,6 +41,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER (ANULLSINK,   anullsink,   asink);
 
     REGISTER_FILTER (BLACKFRAME,  blackframe,  vf);
+    REGISTER_FILTER (BOXBLUR,     boxblur,     vf);
     REGISTER_FILTER (COPY,        copy,        vf);
     REGISTER_FILTER (CROP,        crop,        vf);
     REGISTER_FILTER (CROPDETECT,  cropdetect,  vf);
diff --git a/libavfilter/avfilter.h b/libavfilter/avfilter.h
index 362bbfe2e5..3e1acea542 100644
--- a/libavfilter/avfilter.h
+++ b/libavfilter/avfilter.h
@@ -29,8 +29,8 @@
 #include "libavutil/rational.h"
 
 #define LIBAVFILTER_VERSION_MAJOR  2
-#define LIBAVFILTER_VERSION_MINOR 24
-#define LIBAVFILTER_VERSION_MICRO  4
+#define LIBAVFILTER_VERSION_MINOR 25
+#define LIBAVFILTER_VERSION_MICRO  0
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
                                                LIBAVFILTER_VERSION_MINOR, \
diff --git a/libavfilter/vf_boxblur.c b/libavfilter/vf_boxblur.c
new file mode 100644
index 0000000000..7fb1ec5ba2
--- /dev/null
+++ b/libavfilter/vf_boxblur.c
@@ -0,0 +1,350 @@
+/*
+ * Copyright (c) 2002 Michael Niedermayer <michaelni@gmx.at>
+ * Copyright (c) 2011 Stefano Sabatini
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with FFmpeg; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file
+ * Apply a boxblur filter to the input video.
+ * Ported from MPlayer libmpcodecs/vf_boxblur.c.
+ */
+
+#include "libavutil/avstring.h"
+#include "libavutil/eval.h"
+#include "libavutil/pixdesc.h"
+#include "avfilter.h"
+
+static const char *var_names[] = {
+    "w",
+    "h",
+    "cw",
+    "ch",
+    "hsub",
+    "vsub",
+    NULL
+};
+
+enum var_name {
+    VAR_W,
+    VAR_H,
+    VAR_CW,
+    VAR_CH,
+    VAR_HSUB,
+    VAR_VSUB,
+    VARS_NB
+};
+
+typedef struct {
+    int radius;
+    int power;
+} FilterParam;
+
+typedef struct {
+    FilterParam luma_param;
+    FilterParam chroma_param;
+    FilterParam alpha_param;
+    char luma_radius_expr  [256];
+    char chroma_radius_expr[256];
+    char alpha_radius_expr [256];
+
+    int hsub, vsub;
+    int radius[4];
+    int power[4];
+    uint8_t *temp[2]; ///< temporary buffer used in blur_power()
+} BoxBlurContext;
+
+#define Y 0
+#define U 1
+#define V 2
+#define A 3
+
+static av_cold int init(AVFilterContext *ctx, const char *args, void *opaque)
+{
+    BoxBlurContext *boxblur = ctx->priv;
+    int e;
+
+    if (!args) {
+        av_log(ctx, AV_LOG_ERROR,
+               "Filter expects 2 or 4 arguments, none provided\n");
+        return AVERROR(EINVAL);
+    }
+
+    e = sscanf(args, "%255[^:]:%d:%255[^:]:%d:%255[^:]:%d",
+               boxblur->luma_radius_expr,   &boxblur->luma_param  .power,
+               boxblur->chroma_radius_expr, &boxblur->chroma_param.power,
+               boxblur->alpha_radius_expr,  &boxblur->alpha_param .power);
+
+    if (e != 2 && e != 4 && e != 6) {
+        av_log(ctx, AV_LOG_ERROR,
+               "Filter expects 2 or 4 or 6 params, provided %d\n", e);
+        return AVERROR(EINVAL);
+    }
+
+    if (e < 4) {
+        boxblur->chroma_param.power = boxblur->luma_param.power;
+        av_strlcpy(boxblur->chroma_radius_expr, boxblur->luma_radius_expr,
+                   sizeof(boxblur->chroma_radius_expr));
+    }
+    if (e < 6) {
+        boxblur->alpha_param.power = boxblur->luma_param.power;
+        av_strlcpy(boxblur->alpha_radius_expr, boxblur->luma_radius_expr,
+                   sizeof(boxblur->alpha_radius_expr));
+    }
+
+    return 0;
+}
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+    BoxBlurContext *boxblur = ctx->priv;
+
+    av_freep(&boxblur->temp[0]);
+    av_freep(&boxblur->temp[1]);
+}
+
+static int query_formats(AVFilterContext *ctx)
+{
+    enum PixelFormat pix_fmts[] = {
+        PIX_FMT_YUV444P,  PIX_FMT_YUV422P,  PIX_FMT_YUV420P,
+        PIX_FMT_YUV411P,  PIX_FMT_YUV410P,  PIX_FMT_YUVA420P,
+        PIX_FMT_YUV440P,  PIX_FMT_GRAY8,
+        PIX_FMT_YUVJ444P, PIX_FMT_YUVJ422P, PIX_FMT_YUVJ420P,
+        PIX_FMT_YUVJ440P,
+        PIX_FMT_NONE
+    };
+
+    avfilter_set_common_pixel_formats(ctx, avfilter_make_format_list(pix_fmts));
+    return 0;
+}
+
+static int config_input(AVFilterLink *inlink)
+{
+    AVFilterContext *ctx = inlink->dst;
+    BoxBlurContext *boxblur = ctx->priv;
+    const AVPixFmtDescriptor *desc = &av_pix_fmt_descriptors[inlink->format];
+    int w = inlink->w, h = inlink->h;
+    int cw, ch;
+    double var_values[VARS_NB], res;
+    char *expr;
+    int ret;
+
+    if (!(boxblur->temp[0] = av_malloc(w)) ||
+        !(boxblur->temp[1] = av_malloc(w)))
+        return AVERROR(ENOMEM);
+
+    boxblur->hsub = desc->log2_chroma_w;
+    boxblur->vsub = desc->log2_chroma_h;
+
+    var_values[VAR_W]  = inlink->w;
+    var_values[VAR_H]  = inlink->h;
+    var_values[VAR_CW] = cw = w>>boxblur->hsub;
+    var_values[VAR_CH] = ch = h>>boxblur->vsub;
+    var_values[VAR_HSUB] = 1<<boxblur->hsub;
+    var_values[VAR_VSUB] = 1<<boxblur->vsub;
+
+#define EVAL_RADIUS_EXPR(comp)                                          \
+    expr = boxblur->comp##_radius_expr;                                 \
+    ret = av_expr_parse_and_eval(&res, expr, var_names, var_values,     \
+                                 NULL, NULL, NULL, NULL, NULL, 0, ctx); \
+    boxblur->comp##_param.radius = res;                                 \
+    if (ret < 0) {                                                      \
+        av_log(NULL, AV_LOG_ERROR,                                      \
+               "Error when evaluating " #comp " radius expression '%s'\n", expr); \
+        return ret;                                                     \
+    }
+    EVAL_RADIUS_EXPR(luma);
+    EVAL_RADIUS_EXPR(chroma);
+    EVAL_RADIUS_EXPR(alpha);
+
+    av_log(ctx, AV_LOG_INFO,
+           "luma_radius:%d luma_power:%d "
+           "chroma_radius:%d chroma_power:%d "
+           "alpha_radius:%d alpha_power:%d "
+           "w:%d chroma_w:%d h:%d chroma_h:%d\n",
+           boxblur->luma_param  .radius, boxblur->luma_param  .power,
+           boxblur->chroma_param.radius, boxblur->chroma_param.power,
+           boxblur->alpha_param .radius, boxblur->alpha_param .power,
+           w, cw, h, ch);
+
+#define CHECK_RADIUS_VAL(w_, h_, comp)                                  \
+    if (boxblur->comp##_param.radius < 0 ||                             \
+        2*boxblur->comp##_param.radius > FFMIN(w_, h_)) {               \
+        av_log(ctx, AV_LOG_ERROR,                                       \
+               "Invalid " #comp " radius value %d, must be >= 0 and <= %d\n", \
+               boxblur->comp##_param.radius, FFMIN(w_, h_)/2);          \
+        return AVERROR(EINVAL);                                         \
+    }
+    CHECK_RADIUS_VAL(w,  h,  luma);
+    CHECK_RADIUS_VAL(cw, ch, chroma);
+    CHECK_RADIUS_VAL(w,  h,  alpha);
+
+    boxblur->radius[Y] = boxblur->luma_param.radius;
+    boxblur->radius[U] = boxblur->radius[V] = boxblur->chroma_param.radius;
+    boxblur->radius[A] = boxblur->alpha_param.radius;
+
+    boxblur->power[Y] = boxblur->luma_param.power;
+    boxblur->power[U] = boxblur->power[V] = boxblur->chroma_param.power;
+    boxblur->power[A] = boxblur->alpha_param.power;
+
+    return 0;
+}
+
+static inline void blur(uint8_t *dst, int dst_step, const uint8_t *src, int src_step,
+                        int w, int radius)
+{
+    /* Naive boxblur would sum source pixels from x-radius .. x+radius
+     * for destination pixel x. That would be O(radius*width).
+     * If you now look at what source pixels represent 2 consecutive
+     * output pixels, then you see they are almost identical and only
+     * differ by 2 pixels, like:
+     * src0       111111111
+     * dst0           1
+     * src1        111111111
+     * dst1            1
+     * src0-src1  1       -1
+     * so when you know one output pixel you can find the next by just adding
+     * and subtracting 1 input pixel.
+     * The following code adopts this faster variant.
+     */
+    int x, sum = 0;
+    const int length = radius*2 + 1;
+    const int inv = ((1<<16) + length/2)/length;
+
+    for (x = 0; x < radius; x++)
+        sum += src[x*src_step]<<1;
+    sum += src[radius*src_step];
+
+    for (x = 0; x <= radius; x++) {
+        sum += src[(radius+x)*src_step] - src[(radius-x)*src_step];
+        dst[x*dst_step] = (sum*inv + (1<<15))>>16;
+    }
+
+    for (; x < w-radius; x++) {
+        sum += src[(radius+x)*src_step] - src[(x-radius-1)*src_step];
+        dst[x*dst_step] = (sum*inv + (1<<15))>>16;
+    }
+
+    for (; x < w; x++) {
+        sum += src[(2*w-radius-x-1)*src_step] - src[(x-radius-1)*src_step];
+        dst[x*dst_step] = (sum*inv + (1<<15))>>16;
+    }
+}
+
+static inline void blur_power(uint8_t *dst, int dst_step, const uint8_t *src, int src_step,
+                              int w, int radius, int power, uint8_t *temp[2])
+{
+    uint8_t *a = temp[0], *b = temp[1];
+
+    if (radius && power) {
+        blur(a, 1, src, src_step, w, radius);
+        for (; power > 2; power--) {
+            uint8_t *c;
+            blur(b, 1, a, 1, w, radius);
+            c = a; a = b; b = c;
+        }
+        if (power > 1) {
+            blur(dst, dst_step, a, 1, w, radius);
+        } else {
+            int i;
+            for (i = 0; i < w; i++)
+                dst[i*dst_step] = a[i];
+        }
+    } else {
+        int i;
+        for (i = 0; i < w; i++)
+            dst[i*dst_step] = src[i*src_step];
+    }
+}
+
+static void hblur(uint8_t *dst, int dst_linesize, const uint8_t *src, int src_linesize,
+                  int w, int h, int radius, int power, uint8_t *temp[2])
+{
+    int y;
+
+    if (radius == 0 && dst == src)
+        return;
+
+    for (y = 0; y < h; y++)
+        blur_power(dst + y*dst_linesize, 1, src + y*src_linesize, 1,
+                   w, radius, power, temp);
+}
+
+static void vblur(uint8_t *dst, int dst_linesize, const uint8_t *src, int src_linesize,
+                  int w, int h, int radius, int power, uint8_t *temp[2])
+{
+    int x;
+
+    if (radius == 0 && dst == src)
+        return;
+
+    for (x = 0; x < w; x++)
+        blur_power(dst + x, dst_linesize, src + x, src_linesize,
+                   h, radius, power, temp);
+}
+
+static void draw_slice(AVFilterLink *inlink, int y0, int h0, int slice_dir)
+{
+    AVFilterContext *ctx = inlink->dst;
+    BoxBlurContext *boxblur = ctx->priv;
+    AVFilterLink *outlink = inlink->dst->outputs[0];
+    AVFilterBufferRef *inpicref  = inlink ->cur_buf;
+    AVFilterBufferRef *outpicref = outlink->out_buf;
+    int plane;
+    int cw = inlink->w >> boxblur->hsub, ch = h0 >> boxblur->vsub;
+    int w[4] = { inlink->w, cw, cw, inlink->w };
+    int h[4] = { h0, ch, ch, h0 };
+    uint8_t *dst[4], *src[4];
+
+    for (plane = 0; inpicref->data[plane] && plane < 4; plane++) {
+        int y = plane == 1 || plane == 2 ? y0 >> boxblur->vsub : y0;
+        src[plane] = inpicref ->data[plane] + inpicref ->linesize[plane] * y;
+        dst[plane] = outpicref->data[plane] + outpicref->linesize[plane] * y;
+    }
+
+    for (plane = 0; inpicref->data[plane] && plane < 4; plane++)
+        hblur(outpicref->data[plane], outpicref->linesize[plane],
+              inpicref ->data[plane], inpicref ->linesize[plane],
+              w[plane], h[plane], boxblur->radius[plane], boxblur->power[plane],
+              boxblur->temp);
+
+    for (plane = 0; inpicref->data[plane] && plane < 4; plane++)
+        vblur(outpicref->data[plane], outpicref->linesize[plane],
+              outpicref->data[plane], outpicref->linesize[plane],
+              w[plane], h[plane], boxblur->radius[plane], boxblur->power[plane],
+              boxblur->temp);
+}
+
+AVFilter avfilter_vf_boxblur = {
+    .name          = "boxblur",
+    .description   = NULL_IF_CONFIG_SMALL("Blur the input."),
+    .priv_size     = sizeof(BoxBlurContext),
+    .init          = init,
+    .uninit        = uninit,
+    .query_formats = query_formats,
+
+    .inputs    = (AVFilterPad[]) {{ .name             = "default",
+                                    .type             = AVMEDIA_TYPE_VIDEO,
+                                    .config_props     = config_input,
+                                    .draw_slice       = draw_slice,
+                                    .min_perms        = AV_PERM_READ },
+                                  { .name = NULL}},
+    .outputs   = (AVFilterPad[]) {{ .name             = "default",
+                                    .type             = AVMEDIA_TYPE_VIDEO, },
+                                  { .name = NULL}},
+};